Achieving Low-Noise Renders In Blender Without Relying On Denoising
Setting Up Your Scene Properly
Setting up your Blender scene appropriately from the start is crucial for reducing noise in renders. Careful configuration of light paths, use of portals and planes, and optimization of textures and materials can dramatically cut down on noisy fireflies and splotches.
Managing Light Paths and Bounces
The key setting controlling light behavior in Blender is the Max Bounces under Light Paths. This defines the maximum number of times a light ray can bounce around the scene before being terminated. Lower values like 3-5 cuts down on noise but can result in black splotches where light fails to reach.
A balanced approach is setting the Max Bounces between 8-12 for most scenes. Indirect lighting levels may need to be raised to compensate. Using lower Glossy Bounces relative to Diffuse can reduce fireflies from glossy surfaces.
Using Portals and Planes
Planes and portals are useful for controlling noise from caustic light patterns or preventing indirect light bleeding where it is not desired. By strategically dividing a scene, quality samples can be focused only on key areas.
For example, placing portals between rooms allows separating noisy indirect bounce lighting between environments. Plus, using planes to isolate intense caustic light from a window prevents that noise spreading across the entire scene.
Optimizing Texture and Material Settings
Texture and material settings can contribute to noisy renders in Blender. Issues like fireflies often originate from flawed texture usage or material configuration.
For textures, use formats with 8 to 16-bit depth and avoid excessive contrast or saturation levels. For materials, lower the Roughness value to 0.3 or below if seeing splotchy fireflies on glossy surfaces.
Sampling Techniques for Clean Renders
In addition to environment setup, leveraging core sampling techniques in Blender is key for lowering render noise. This includes carefully increasing sample counts in critical areas, using adaptive sampling to focus samples, and controlling filters and clamping.
Increasing Sample Counts Strategically
Higher sample counts equals lower noise but also greater render times. To balance this, selectively increasing samples only for critical areas can keep noise down without excessive render durations.
For example, in a room you may only need 64-128 samples for walls but would want 500-1000 samples for detailed objects like furniture. Using object or material overrides allows controlling samples precisely.
Using Adaptive Sampling
Adaptive sampling is useful for optimizing sampling by directing more samples towards complex areas and fewer for easy areas. This focuses computations where needed most.
Enable Adaptive Sampling under Render Properties then set key parameters like Noise Threshold and Correction Contrast. This guide samples towards noisy areas and reduces samples for clean patches.
Controlling Clamping and Filtering
Clamping and filtering settings under Sampling help reduce fireflies and noise patterns. Lowering the Clamp value controls hot pixels while higher Filter sizes smooth variation between samples.
Careful use of these tools can eliminate stray noisy pixels while retaining detail. Useful combinations are Clamp of 2.0 with a Filter of 1.5 or Clamp 0.5 and Filter at 2.0.
Denoising as a Last Resort
While best avoided until all other options are exhausted, Blender does provide high-quality denoising tools. The non-realtime denoiser can clean up leftover noise with optimized parameter settings.
Using the Non-Realtime Denoiser
Under Scene Properties then View Layer, Blender’s non-realtime Denoising filter averages pixel values to smooth noise using special AI algorithms. This is very effective for final reductions.
Enable Denoising, set Feature Strength between 8 and 15 then fine-tune the Diffuse, Glossy, Transmission and Subsurface values individually until the best balance of noise removal versus lost detail.
Optimizing Denoiser Settings
Higher denoising feature strength values eliminate more noise but runs the risk of overblurring image details. Start with low values first then increase steadily only if necessary.
Also know the limits of denoising – extremely high sample counts like 5000+ may exceed the capability of the filter to further improve. Target moderate sample counts instead for better compatibility.
Combining With Other Noise Reduction Methods
Get superior results by combining the Blender denoiser with lower sample counts plus all other noise reduction techniques mentioned earlier. This balances rendering time versus quality.
Use all available tricks – managed bounces, portals, optimized textures, clamping, etc. – first to lower samples to 250-500 then denoise for final cleanup. Images will retain detail at a fraction of the render time.
Example Scene and Node Setups
Analyzing example files with low-noise configurations in Blender demonstrates these techniques in action. We examine portal usage, denoiser settings, and sampling standards for clean renders.
Low-Noise Studio Lighting Demo
For this studio lighting test with glass and metal models, indirect ray bounces were limited to 6 diffuse/3 glossy. Just two area lamp fills are used with higher intensity to counter fewer bounces.
Smoke and fog domains isolated inside containment planes prevent them contaminating the scene. Other planes also segment the render regions to control noise spread.
Clean Outdoor Render With Portals
In this outdoor suburban scene, a house exterior displaying intense sunlight through trees demonstrates portal usage to minimize noise.
Planes isolate the incoming sunlight to just one side of the house while allowing softerFill illumination on the opposing face. Careful light path planning achieves clean rendering.
Complex Scene Using Denoising and Sampling
The final demonstration features a extensive 5-room inner city apartment with many geometric details for potential noise issues.
Denoising enabled at Feature Strength 10 and 400 samples blurs residual noise after techniques like light portal isolation between rooms. The sampling threshold balances time versus quality.
